Alscholarines A and B, two rearranged monoterpene indole alkaloids from Alstonia scholaris

Org Biomol Chem. 2023 Oct 18;21(40):8190-8196. doi: 10.1039/d3ob01424j.

Abstract

Alscholarines A and B (1 and 2), two unprecedented rearranged monoterpene indole alkaloids, were isolated from Alstonia scholaris. Alscholarine A (1) features an imidazole ring fused with a rearranged vallesamine-type alkaloid possessing an unparalleled 6/5/6/6 tetracyclic skeleton through an unprecedented C7-C-19 connectivity. Alscholarine B (2), incorporating an unusual 7-oxa-1-azabicyclo[3.2.1]octane moiety, represents a unique rearranged vallesamine-type alkaloid with a 6/5/6/6/5 ring system via an unprecedented C-6-C-20 connectivity. Their structures were established by spectroscopic analysis, X-ray crystallography, and quantum-chemical calculations. Their plausible biosynthetic pathways were proposed. The vasorelaxant and anti-inflammatory activities of them were also evaluated. Compounds 1-3 showed moderate vasorelaxant activities.

MeSH terms

  • Alkaloids*
  • Alstonia* / chemistry
  • Indole Alkaloids / chemistry
  • Indole Alkaloids / pharmacology
  • Molecular Structure
  • Monoterpenes / pharmacology
  • Vasodilator Agents

Substances

  • Monoterpenes
  • Indole Alkaloids
  • Alkaloids
  • Vasodilator Agents